Baldur's Gate 3: If you decided happily ever after wasn’t for you, there’s an assortment of evil ending cinematics new to Baldur’s Gate 3, arriving with Patch 7.
I'd say that is mostly accurate. Most of the quests revolved around "good" actions. There's a few that's "neutral". And only some that are clearly "evil". I would say, you'd get the the game much faster doing evil things because... you sort of shortcut a lot of "quests" (either strait up ignoring the request, or just killing them).
spoiler
Example, the fight in the House of Grief, with an evil run with Shadowheart... this place becomes much easier since you only fight about half the room and the other half now helps. And if you do some evil stuff at the Tribunal, there's a special vendor. And in Act 3, siding with Ethel grants you a different reward. So there are some benefits that only evil acts can get. But also, in act 1, there's a sword that's exceptionally good sword at Waukeen's Rest.
But on the whole, if you start off evil early, many of the NPC's that would chain to later quests... well... they may not exist anymore. But it's not lacking fun. Being evil in of itself is an interesting play through. Especially, because the dialog you see will be very different from most other runs. I didn't hate the evil runs despite there being very few positive interactions for being evil. But the endings were very much lacking when compared to a "good" run.
Thanks for the reply! It's a fairly common problem in games like this where the "evil run" is less fun because so many decisions just lead to cut off branches of story or characters missing. Writing compelling evil options in an RPG is genuinely difficult - and not common.
Let's hope the new endings are more satisfying, at least!